The specific heat of thin films near theλ-transition: a Monte Carlo study of an improved three-dimensional lattice model

Abstract

We study the finite size scaling behaviour of the specific heat of thin films in the neighbourhood ofthe λ-transition. To this end we have simulated the improved two-componentϕ4 model on the simple cubic lattice. We employ free boundary conditions in theshort direction to mimic the vanishing order parameter at the boundaries of a 4He film. Most of our simulations are performed for the thicknessesL0 = 8,16 and32 of the film. It turns out that one has to take into account corrections to obtain a good collapse of the finite size scaling functions obtained from differentL0. Our results are compared with those obtained from experiments on thin films of 4He nearthe λ-transition, from field theory and from previous Monte Carlo simulations.